A screening device for the wet classifying of bulk material is known from the German Patent No. 1,301,226, and comprises several stationary screen baskets arranged one above the other. The solid-liquid mixture is introduced tangentially at high speed in the upper area of the screen basket. The mixture runs downwards into a helical flow in the conical screen basket and at the same time releases the liquid to the slotted hole screen. At the start, that is immediately after the mixture is fed, the screening performance is comparatively low. Also, the mixture flows off too quickly in the lower area through the central, lower basket opening without being adequately processed in this area.